The undercutting and pointing of hobbed double involute gear teeth

After meshing interference and cutler interference are analyzed, a general method is presented for the determining minimum number of teeth that can be cut in a double involute helical gear without undercutting by a rounded-tooth tip hob. The study is completed according to the cutting engagement of the hob and a gear in transverse plane. It points that transverse path of contact does not pass through the center of ellipse of the rounded-tooth tip hob. The study is carried out combining the pointing with the minimum number of teeth to avoid undercutting. An example is employed to prove that the pointing and undercutting of the double involute gear can be avoided at the same time.